题目

 A 10-year-old boy decided to study judo despite the fact that he had lost his left arm in a terrible car accident.    The boy began lessons with an old Japanese judo master. The boy was doing well, so he couldn't understand why, after three months of training, the master had taught him only one move. Sensei, the boy finally said, shouldn't I be learning more moves? This is the only move you know, but this is the only move you'll ever need to know, the sensei replied. Not quite understanding, but believing in his teacher, the boy kept training.    Several months later, the sense写出具有下列意义的化学符号 两个氯原子________，三个氢分子________， 四个醋酸分子________，正三价铝元素________， 氯离子________，两个铁离子_________．